The emergency of switching to an online learning model due to the COVID pandemic impacted the educational process in of schools world wide. We conducted an anonymous survey at the elite high schools in Serbia whose students won 45 medals at international Olympiads in mathematics, physics, and computer sciences in the last 4-year period (2019-2022). The impact of switching from in-person to online learning on the achievement of the gifted students was analyzed. The results of the research revealed a downward trend in the final grades and achievements in international Olympiads, which persists even after returning to the face-to-face educational model. This trend is confirmed by calculation of the Pearson correlation coefficient (-0.62) between school years and achievements in international mathematical Olympiads, international physics Olympiads, and international Olympiads in informatics. Gifted students' satisfaction with online learning during the COVID pandemic was also analyzed using content analysis of open-ended questions. The surveyed gifted students showed a high level of self-criticism and maturity by expressing their opinion about online learning. In the group of gifted students, there is a higher level of agreement about harmful consequences of online learning on the level of their education and work habits than in other research conducted on similar topics. Moreover, the level of agreement is in a positive correlation with students' achievements and final grades.